Field of the Invention
This invention relates to improvements in a rotary screen printer. More particularly, the rotary screen printer is a mechanized screen printing machine where an operator installs a product and the product is precisely rotated around to various printing stations for application of colors, textures, coatings or drying.
Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98
Over the years screen printing has evolved from an operator manually positioning a single such as a shirt on a platen, lowering a patterned silk screen and screening a single color or color blend. The applied color(s) then typically air dried and application of additional color(s) were applied in the same manner. This traditional silk screen printing of textiles and other supports has well-known limitations of resolution and rendering. One of the problems is with the use of a reasonable maximum number of silk-screen printing stencils needed for the sequential application of as many silk-screen printing inks or pastes, each application needing a drying step.
With more modern printing methods need to be developed. Some solutions such as digital print by a common inkjet plotter color graphical compositions on dark or black supports. Another limitation of digital printing is the impossibility of forming features in relief or of introducing special effects such as for example: glitters, glues, expanded materials, in order to obtain peculiar esthetical effects in the drawing or graphical image to be reproduced on the printable support.
Traditional silk-screen printing technique permits the use of special inks or pigmented pastes and therefore the printing may be done on any surface even black without any problem. Silk screen printing technique have trouble with the presence on the printing area of reliefs and/or depressions as may be produced by the presence of sewing lines, hems, pockets and the like in the printing area. With these challenges, registration of the textile is critical to ensure that each color is placed in the required location as the textile progresses through the printing process.
A number of patents and or publications have been made to address these issues. Exemplary examples of patents and or publication that try to address this/these problem(s) are identified and discussed below.
U.S. Pat. No. 3,427,964 that issued on Feb. 18, 1969 to M. Vasilantone discloses a stencil printing machine. This machine has a stretcher assembly which is pivotal vertically and a horizontally rotatable platen assembly having a plurality of baseboards where the stretcher assembly is indexed for multi-colored printing. This patent requires manual indexing of the stretcher assembly and either requires the operator to move between each of the colors or for four operators to print a single shirt.
U.S. Pat. No. 7,231,873 that issued on Jun. 19, 2007 to Luigi Macchi discloses a print carousel for double technology silk-screen and digital color printing. This machine has a plurality of print stations that are rotary indexed with a pneumatic or similar indexing system and then the silk-screen in brought down and the ink applied. While this system uses a rotary indexing printer the drive mechanism is not a stepper motor that can both ramp to indexing rate and provide a positive position lock.
U.S. Publication Number 2006/0249039 that issued on Nov. 9, 2006 to Alon Feldman et al., discloses a combined stencil and digital printing system. This system also uses a pneumatic actuator to index the table and a position lock to prevent undesirable movement of the table position while the object is being printed with either an ink jet or a silk screen printing stencil. While this publication discloses a rotary printing table, the table is indexed with a pneumatic actuator and requires a lock to hold the table in a ridged position.
What is needed is a rotary screen printing machine where the indexing of the table is performed with a stepper motor drive to provide reliable acceleration and deceleration of the rotating platen(s) and further provides a ridged lock without the arms being compliant.